The 50psi experiment

[star_deceiver]

With only about a month of life left in the stock tires before the winter's go on and the RS-A's go to the giant tire fire in the sky... I've jacked them to 50psi (51 psi max on the sidewall).The ride's a little rougher then the usual 42 psi that I was running. The car's body roll is a little less. But this is an experiment in my commute mileage, 20km round trip 50/50 city/highway. Tire wear isn't an issue, handling isn't an issue.Winter's are going on as soon as the temp start's dropping below -5C in the morning... or the 2nd week of November.

[vit]

"usual 42 psi"? I don't find that very usual.

[Sublimewind]

Quote, originally posted by vit »"usual 42 psi"? I don't find that very usual.Ditto..

[Bedlam]

Quote, originally posted by star_deceiver »The ride's a little rougher then the usual 42 psi that I was running. 42psi might be fine for road racing and then airing down after. That is not a good thing to do to your tires continuously. 32-36 psi cold is usually a good target. Keep in mind, these cars are so light weight (~2700lbs) that they can easily get by on less tire pressure than the average 3300-3600lbs sedans.

[Old Tele man]

...but, if tire *life* isn't as important as fuel economy, then jacking up the tire pressure is OK, so long as you don't exceed the sidewall "Maximum Pressure" value.

[keithvibe]

Quote, originally posted by vit »"usual 42 psi"? I don't find that very usual.Quote, originally posted by Sublimewind »Ditto.. i run 40psi without any abnormal wear issues

[Old Tele man]

...running 40 psi on the OEM Eagle RS-A's on my '09 Vibe too.

[cptnsolo77]

I have run 37PSI ( cold ) for 3 years & havent experienced any issues. In fact I get better MPG at 37PSI.Car doesnt feel so "mushy" in turns either.

[star_deceiver]

Quote, originally posted by cptnsolo77 »Car doesnt feel so "mushy" in turns either.I like that non-mushy feeling!!!The tires are worn more on the outside of the fronts then elsewhere and feathering probably due to the fact that the tires have only been rotated twice in their life of non-winter driving. I'm not at the wearbars yet and probably won't be by the time they come off but they won't be going back on in the spring.

[Zimm]

i run 38 psi in my stock RSA's. at 32-34, the handling is slushy and MPG is noticeably worse-between 20 and 40 miles less per tank.

[Kincaid]

I need to bump my tires up. My gas mileage is pretty sucky.I would think handling might suffer a bit - doesn't gross overinflation reduce the contact patch? In the past, with other vehicles, I've certainly noticed how much easier the steering is in parking lots.

[star_deceiver]

Quote, originally posted by Kincaid »I would think handling might suffer a bit - doesn't gross overinflation reduce the contact patch? I've certainly noticed how much easier the steering is in parking lots.Yes, and yes! Handling does suffer and steering is much easier (not that it was difficult before...).

[cq358]

I did pump up to 37psi for almost 4 months. I sees there are more crack showing on the thread block. Now i put it back to 35psi.I have a feeling that if you pump it up too high it actually wear out the suspension bushings.. I would rather replacing the tires than damaging lower control arm bushings..There are many cases of late model sienna and Camrys has unseat their control arm bushings..

[star_deceiver]

Quote, originally posted by cq358 »I have a feeling that if you pump it up too high it actually wear out the suspension bushings.Cool!!! An excuse to replace them all with some urethane bushings!!!Tank 1: Driving normally 80/20 City/Highway 7.4 L/100kms 31.7mpgTank 2: (Driving my normal speed for this route - 557kms on 39.29L) 90/10 Highway/City Vernon --> Downtown Vancouver to Chilliwack with an average highway speed of 75-80 mph 7L/100kms 33.6mpgCity mileage is about the same but I used a lot less gas on the freeway! The trip from Vernon to Downtown Vancouver to Chilliwack usually puts me well into the low fuel warning (if I even make it that far) as speeds on the unpatrolled freeway between West Kelowna and Hope are "Whatever you think is best".....

[DressedInBlack]

did you make the switch yet?

[star_deceiver]

Not yet. It was 15C today and has been nowhere near freezing, yet...Besides... I still have to "Kill" the RS-A's....

[star_deceiver]

Tank 3: 7.1L/100km 50/50Tank 4: 7.6L/100km 80city/20hwyAnd the Winters are on. I can say that running the tires at 50psi did save some gas and definatly stiffened the ride, but not that much more then the usual 40/42psi I ran them at. The winters are at 40psi right now (44max).The front tires were worn down to the wearbar on the outside and 3/32 on the inside. Rear tires were 4/32.I got about 43000kms on the RS-A's... Now to save up for some new rims so I can keep the winters on the steelies!!!

[ponta2147]

Watching the Mythbusters episode dealing with tire pressure...15% (40psi) overinflation had about 6% better fuel economy, whereas ridiculous overinflation (60psi) got it to about 8%... hehe it just made me think of this thread.

[lovemyraffe]

Quote, originally posted by ponta2147 »Watching the Mythbusters episode dealing with tire pressure...15% (40psi) overinflation had about 6% better fuel economy, whereas ridiculous overinflation (60psi) got it to about 8%... hehe it just made me think of this thread.Watched that episode too. I usually run 36 psi.

[star_deceiver]

IDK... I consider overinflation anything over the max psi of the tire...

[DressedInBlack]

Quote, originally posted by star_deceiver »Tank 3: 7.1L/100km 50/50Tank 4: 7.6L/100km 80city/20hwyAnd the Winters are on. I can say that running the tires at 50psi did save some gas and definatly stiffened the ride, but not that much more then the usual 40/42psi I ran them at. The winters are at 40psi right now (44max).interesting...!

[ou.grizzly]

More air in tires = less tread on the pavement = less surface contact = less friction = improved mileage???

[ParknVibe]

Quote, originally posted by ou.grizzly »More air in tires = less tread on the pavement = less surface contact = less friction = improved mileage???.....AND TAKE OFF..... off the road!!!!I'll stay between 32 to 34 psi. The recommended tire pressure was given based on the estimated load applied to each tire. If the car is 3000 lbs then lets assumed 750 lbs on each tire plus the max live load of the passengers and cargo. say 200 lbs per tire. That will be about 950 lbs. per tire for a standard Vibe. Thus...32 psi for the Vibe.If the car was 4000 lbs curb weight plus 800 lbs live load, then the weight on each tire will be 1200 lbs. So in this case the manufacture may recommend a higher tire pressure to support this given load, say 35 psi.Driving a car with a very high tire pressure is dangerous for your safety especially when the road is wet or icy. It's bad for the tire because of how it will wear. And it is bad for the car's suspension. The maximum side wall tire pressure printed on the tire is the most the tire can handle just before it EXPLODES due to the forces applied to it.

[star_deceiver]

Quote, originally posted by Ivibe »The maximum side wall tire pressure printed on the tire is the most the tire can handle just before it EXPLODES due to the forces applied to it.Not quite...The maximum COLD pressure on the sidewall is where you need to have the pressure to support the tires maximum rated load capacity.Quote, originally posted by Ivibe »Driving a car with a very high tire pressure is dangerous for your safety especially when the road is wet or icy. /QUOTE]That's describing RS-A's in general. Besides they hydroplaned when they were brand new and at the proper 32psiAnd IMHO if you're driving Goodyear RS-A's on icy or snowy roads then you're a ____ing MORON and deserve to be in the ditch, whatever psi you're running!!![QUOTE=Ivibe]It's bad for the tire because of how it will wear. And it is bad for the car's suspension. These tires were at the end of their life, about 4/32 left at the beginning of this experiment. The suspension did work harder, but we have very good roads here/very few potholes, but no matter what you do the shocks won't last forever!Quote, originally posted by ou.grizzly »More air in tires = less tread on the pavement = less surface contact = less friction = improved mileage???Improved mileage, but not that much... maybe $2 a tank. You'd save more money by cutting back on your cell phone or other luxuries!

[star_deceiver]

In comparison:First full tank with the winter tires: 549.2km on 44.812L - 8.1L/100km or 29 MPG. 60/40 C/H. Not bad considering the weight of the studded tires/winter gas/snow and ice, ect!!!

[TONY TAT2]

Was runnen 36,just jacked em up to 40.